Low-melting Glass Research Articles

Effect of SrO content on microstructure of Bi2O3-B2O3-ZnO-BaO-SrO low-melting glass frit and joining performance of sodalime glass substrates

We studied the feasibility of using Bi-based lead-free glass paste as bonding material on soda-lime glass substrates, without any activation preparation on the bonding surfaces. In order to fabricate Bi2O3-B2O3-ZnO-BaO-SrO system low-melting glass frit, quenching is performed using deionized water after melting using a muffle furnace. Glass paste consisting of glass frit mixed with organic solvent is deposited on the surface of the soda-lime glass substrate by screen printing, and the sealing of the glass substrate is finally achieved at the bonding temperature (500 °C). we discuss the properties of glass powder, the joint microstructure of irregular amorphous glass, the shear properties and the glass frit bonding mechanism based on the characterization results of DSC, XRD, FTIR, Raman, XPS, SEM and TEM. Furthermore, the investigation concentrated on mechanical properties and microstructural characterization of the joined area with two silica substrates. As the SrO content increased from 0 to 3 mol%, Tg increased from 396 °C to 418 °C with increasing SrO content. Accompanied by an increase in SrO content from 1 mol% to 2 mol%, the room-temperature shear strength of the glass specimens increased from 28.5 to 45 MPa. The growth of Bi24B2O39 crystallites precipitated at the interface was studied.

Glass-ceramic composites for high-power white-light-emitting diodes

In this paper we report on the study of sintered ceramic composites based on a low melting glass in which ZnO nanocrystals and commercial YAG:Ce3+ phosphor are embedded. A low Tg is necessary to avoid high temperature sintering which can damage the optical properties of the embedded phosphor, while ZnO is introduced to increase the thermal conductivity of the system. The compositions have been optimized in terms of stability, sintering efficiency and thermal conductivity. Selected samples were optically characterized using a GaN high power multimode 450 nm Laser Diode, with a maximum output power of 1.6 W at 1.5 A.

Low-melting phosphate glasses as flame-retardant synergists to epoxy: Barrier effects vs flame retardancy

In this research, low-melting phosphate (LMP) glasses (G1, G2, G3) were employed as green flame-retardant synergist additives in epoxy (EP)/ammonium polyphosphate (APP) composite. To investigate their performance as flame-retardant additives, comprehensive fire tests and characterizations were carried out, including limiting oxygen index test, UL-94 vertical burning test, cone calorimeter test, real-time temperature detection, X-ray microtomography, and char residue strength analysis. A prominent improvement of flame-retardant properties was observed in EP composites containing LMP glasses. EP/9%APP/1%G1 reached V-0 rating in UL-94 test and showed a decreased peak heat release rate by around 40% over EP/10%APP in the cone calorimeter test. It found that LMP glasses mainly showed the physical barrier effect in the condensed phase flame retardancy. Interestingly, via simulating different combustion temperatures, LMP glasses reveal different flame-retardant performance. The mechanism was further elucidated as: A match between the LMP glass phase-transition temperature range and the combustion temperature contributed to the optimized flame-retardant performances. This result provided enlightenment for the design and application of phase-transition additives toward improving the flame-retardant properties in polymer composites.

Low melting oxide glasses prepared at a melt temperature of 500\xa0\xb0C

Transparent low-melting inorganic glass is an attractive industrial material based on its high thermal and light resistance compared with conventional engineering plastics. If the melting temperature of inorganic glass could be decreased, the doping of guest materials or compression moulding on the glass surface would be easier. Although phosphate glass is considered as a potential candidate because of its transparency in the visible region and low-melting behaviour, water durability often becomes a problem for implementation. Here, we prepared inorganic low-melting phosphate glass at a temperature of 500 °C via a melting and quenching methodology. It was found that tin-doped phosphate glasses exhibited higher thermal and light resistance properties than polycarbonates. Colourless transparent oxide glasses without organic components are capable of bringing about new possibilities for the application of inorganic glasses.

Energy saving technology for sintering of black bricks from high-siliceous clay

AbstractThe low-temperature synthesis of bricks prepared from high-siliceous clays by the method of plastic molding of blanks was used. For the preparation of brick blanks, binary and ternary mixtures of high-siliceous clays, black sand, and bottle glass cullet were used. Gray-black low-porosity and high-porosity ceramics was obtained by sintering under conditions of oxygen deficiency. It has been established that to initiate plastic in mixtures containing high-siliceous clay, it is necessary to add montmorillonite/bentonite additives, carry out low-temperature sintering, and introduce low-melting glass additives with a melting point ranging from 750 to 800 °C. The performed investigations have shown that the sintering of mixtures with a total content of iron oxide of about 5 wt% under reducing conditions at Tsint. = 800°C for 8 h leads to the formation of glass ceramics consisting of quartz, feldspars, and a phase. The main sources of the appearance of a dark color is the formation of [Fe3+O4]4- and [Fe3+O6]9- anions in the composition of the glass phase and feldspars. By changing the contents of clay, sand, and glass in sintering, it is possible to obtain two types of ceramic materials: (a) in the form of building bricks and (b) in the form of porous fillers.

The use of regression models to describe the temperature coefficient values of linear expansion and technological temperatures of CaSO4-KPO3-Na2B4O7 low-melting glass system

Low-melting noncrystallizing glasses are used as solders for connections of various metallic and nonmetallic parts. However, theoretical data on glass formation and physical parameters of low-melting glasses are still limited. The use of modelling allows to simplify the selection of a glass system as a solder by the mathematical description of the dependencies of both that the temperature coefficient values of linear expansion and other specific temperatures, which are necessary for a practical application. Therefore, the fourth-order regression polynomial models are offered for describing dependences of the temperature coefficient values of linear expansion, the softening temperature and the glass transition temperature from the component concentrations of the CaSO4-KPO3-Na2B4O7 low-melting glass system in the glass formation region. The model involver both pair and ternary interactions of the glass system’s components. The analysis of the obtained results showed that the concentration of the CaSO4 component has the highest effect on the temperature coefficient values of linear expansion.

Lead-free low-melting-point glass as bonding agent for TiO2 nanoparticles

This work is a study of the properties of TiO2-anatase nanoparticles attached by a low-melting point inorganic glass (530°C). Unlike other low-melting glasses, this composition does not contain any toxic metal. Likewise, it shows an excellent wettability on ceramic nanoparticles. A small addition of 5 vol% of glass remarkably enhances the mechanical strength of the composites with respect to pure TiO2 calcined at the same temperature, becoming twice this value. Self-cleaning properties analyzed using the methylene blue 385 nm UV-A photodegradation test showed that, after different UV-light periods, the photo-efficiency of TiO2-anatase was not altered by the presence of this glass.

Effect of BaO on the structure and properties of bismuth-based low-melting glasses

ABSTRACT The effect of BaO on the structure and properties of bismuth-based low-melting sealing glasses (Bi2O3–B2O3–ZnO–SiO2–Al2O3–BaO) were investigated by FTIR, 27Al NMR and DSC. The results showed that when BaO content was less than or equal to 3 wt-%, BaO provided (O2–) free oxide ions, which made [AlO6] transform into [AlO4] and made [BO3] transform into [BO4]. The increase of [AlO4] and [BO4] enhanced the network structure and decreased the thermal expansion coefficient of glass-ceramic. But when BaO was more than 3 wt-%, a large amount of Ba2+ , considered as an external body of network, entered the gap of glass network and weakened the existing bridge oxygen vibration in the glass structure and increased the thermal expansion coefficient. Besides, the crystallisation ability of glasses would be promoted by increasing the heat treatment temperature or the BaO content. The formation of BaAl2Si2O8 crystal would improve the acidity resistance of the glass-ceramic to a certain extent.

Spectroscopic and dilatometric analysis of low-melting bismuth borate glasses in the Bi2O3–BaO–Li2O–B2O3 quaternary

Bismuth borate glasses with (25 + x)Bi2O3–15BaO–10Li2O-(50 – x)B2O3 (where x = 0, 10, 20, 30 in mol%) compositions have been prepared by the standard melting technique, and characterized by X-ray diffraction (XRD), UV/Vis optical absorption (OA), thermal/dilatometric analysis, Fourier transform-infrared (FT-IR) spectroscopy, and X-ray photoelectron spectroscopy (XPS). The XRD data confirmed the amorphous nature of the glasses in the 25–55 mol% Bi2O3 range, while the OA evaluation revealed a red shift in the glass absorption edge. A decrease in the optical band gap energies with increasing bismuth content was indicated by a Tauc plot assessment of the OA data. The thermal characterization showed that the coefficient of thermal expansion increased with bismuth oxide concentration, whereas the glass transition and softening temperatures decreased. However, these trends were not monotonic, but showed a tendency to plateau. The analyses by FT-IR and XPS (O 1s) pointed to structural rearrangements induced by the higher Bi2O3/B2O3 ratios, basically concurring with the evolution of BO3 units toward BO4 tetrahedra and the increase in non-bridging oxygens in the glasses. The evolution of the thermal properties was ultimately indicated to be linked with the structural changes.

Precipitation of CsPbBr3 quantum dots in borophosphate glasses inducted by heat-treatment and UV-NIR ultrafast lasers

Low-melting borophosphate glasses were fabricated via melt-quenching and then CsPbBr3 quantum dots (QDs) were synthesized in the glasses by heat-treatment and UV-NIR ultrafast lasers irradiation. CsPbBr3 QDs embedded glasses obtained by heat-treatment were confirmed by X-ray diffraction patterns, TEM images and spectral analyses and behaved excellent thermal and moisture stabilities. Moreover, the behavior of lasers-induced crystallization on the surface and interior of glasses is greatly different. CsPbBr3 QDs could directly be precipitated on the surface of glasses by using low peak power ultrafast lasers irradiation and the subsequent heat-treatment would lead to the reduction of nanocrystalline size because there are defects and crystal nucleuses on the surface of glasses. However, the irradiation of high peak power ultrafast lasers could only nucleate inside glass because of the lack of nucleation points inside glasses and the subsequent heat-treatment was required to precipitate CsPbBr3 QDs. The higher the peak power of ultrafast lasers, the stronger the luminescence intensity of CsPbBr3 QDs and the longer its fluorescence lifetime.

Effects of low-melting glass powder on the thermal stabilities of low infrared emissivity coatings

Effects of low-melting glass powder on the thermal stabilities of low infrared emissivity coatings

Effects of low-melting glass powder on the thermal stabilities of low infrared emissivity Al/polysiloxane coatings

In this study, low infrared emissivity coatings with good thermal stabilities were fabricated using silicone resin as adhesive, flake aluminum powder as pigment, and low-melting glass powder as functional filler. The effects of the low-melting glass powder on the adhesions, thermal expansions, and infrared emissivity of the coatings were systematically investigated. In addition, the surface microstructures and thermal stability mechanisms of the coatings were analyzed in detail. Mechanical tests showed that the addition of the low-melting glass powder to the Al/polysiloxane coating enhanced its adhesion after a high-temperature treatment due to the mechanical interlocking of the particles by the secondary film-forming low-melting glass. Thermal analysis indicated that the oxidation resistance of the coating could be improved by the film-forming low-melting glass powder. The low-emissivity coating with a low-melting glass powder content of approximately 15 wt.% and Al/polysiloxane ratio of 1.5 exhibited good thermal stability. The adhesion of the coating increased to 9.0 ± 0.4 MPa after heating at 500 °C. When the content of the low-melting glass was increased from 0 to 15 wt.%, the oxidation exothermic peak of the coating shifted from 590 to 625 °C at a pigment/binder ratio of 1.5. The infrared emissivity of the coating was 0.25 after heating at 600 °C.

Low melting glass as adhesive and insulating agent for soft magnetic composites: Case in FeSi powder core

FeSi/glass composites with different glass content by using low melting glass as adhesive and insulating agent are prepared, and their magnetic properties are investigated. SEM morphology shows that the glass particles between different FeSi spheres deform into flakes after heat treatment, which reveals that glass powder acts as adhesive and insulating agent in the composites. The FeSi/glass composites have high saturation magnetization (up to 210 Am2/kg), low magnetic losses (less than 2100 kW/m3 at 100mT and 100 kHz) and moderate permeability. The moderate eddy current loss obtained by losses separation further indicates that the eddy current between different FeSi spheres is effectively blocked by glass. The advantages of this new preparation process of SMCs are also discussed.

Development of an energy-saving technology for sintering of bricks from high-siliceous clay by the plastic molding method

In the work, the possibility of using the method of plastic molding of blanks and realizing an energy-saving sintering of building bricks from high-siliceous clays have been considered. It has been established that the addition of sand containing a small amount of montmorillonite to such clays makes it possible to perform of plastic molding, and the introduction of low-melting glass additives allows sintering of bricks at 800 °C for 8 h. The data of X-ray diffraction analysis and IR spectroscopy have shown that the synthesized material contains quartz, feldspar, and glass phase, i.e., glass ceramics has been formed. The basis of low-temperature sintering is the formation of a low-temperature eutectic between the molten glass, feldspars, and silica. It has been established that the density, porosity, water absorption, and mechanical properties of ceramics depend on the ratio of the components in the initial mixtures. The developed technology has made it possible to synthesize high-quality building bricks from high-siliceous clays under low-temperature sintering conditions.

Production of an optical coating of low-melting glass for modern devices

The increasing pace of development of new devices obliges electronics manufacturers to apply new technologies in order to be competitive. The use of additive technologies allows manufacturers to quickly adapt to the release of new products. In this work, a computer vision system was developed for the automated manufacturing of an optical coating of low-melting glass. The vision system finds the object on which it is necessary to apply for the glass melt and positions the glass dispenser (reactor capillary) over this object, also controlling dispensing of the glass melt. The article reviews the class of low-melting glasses with components PbO, Bi2O3, Bi2(Cl/Br/I)3 in the range of crystallization temperatures of 100–450 °C. From this class, it is possible to choose glass with the necessary physical parameters and a crystallization temperature at which the glass melt does not harm the component on which the melt will be applied.

Effect of Gamma Irradiation on High Lead Borate Glass Doped with Tungsten Oxide

X-ray, Ultraviolet and Fourier Transform infrared spectral properties of tungsten ions doped in a host lead borate glass have a composition [60%PbO and 40%B2O3 weight%] was studied. Effect of gamma irradiation on the prepared glass samples was surveyed. Amorphization of the studied glass samples have been checked by X ray. Deep inspection for density, molar volume, UV and FTIR for base glass and tungsten oxide with different concentrations (0.15-2.28) weight% proved that the tungsten ions are pronounced as structural groups mostly in the hexavalent W6+. The constancy of optical absorption spectral curves reversed the shielding behavior for this combined glass towards successive gamma irradiation. Glasses containing high lead oxide content are extensively used for multi-applications including lead crystal glass and some special optical glasses, low-melting solder glasses and radiation protection windows and even in immobilization of radioactive nuclear wastes.

Fusible Glass Based on Glassy Chalcogenide Type Systems Ge-S(Se)Br, Ge-S(Se)I

Theoretical and practical results on the preparation and investigation of low-melting glasses using the example of glassy chalcogenide glasses of the Ge-S-Br, Ge-Se-Br systems are presented and summarized. On the basis of fundamental properties of matter, correlations were identified with uniform positions. The glass formation regularities in the indicated chalcogenide and oxyhalide systems were determined. Areas and compositions of low-melting chalcogenide and oxyhalide glasses were considered. Approaches to obtaining of thermostable and difficult to crystallize low-melting glasses were found. Areas of their practical application were identified. On the basis of the obtained data, approaches and criteria for obtaining compositions of low-melting chalcogenide and oxide glasses with practically useful properties are formulated.

Effective Diagnostics of Internal Defects of Diamonds in the near Infrared Range on the Basis of Immersion Medium Made from Low-Melting Chalcogenide Glass

This paper describes a method for detecting defects inside high-refractive index gems. This method consists in immersion of a precious stone inside low-melting chalcogenide glass. After cooling, molten glass turns into a solid phase and is an optical cube. This cube can be photographed in layers and using OctoNus equimpment a 3D model of gemstone defects can be built. The proposed method allows you to effectively and accurately determine the coordinates of the defects in diamond and to offer the most profitable option for polishing a precious stone.

Composite Materials Based on F-4MB Fluoroplastic and Low-Melting Oxyfluoride Glass

Physicochemical properties of materials obtained via the extrusion blending of oxyfluoride glass with the composition 3B2O3 · 97(40SnF2–30SnO–30P2O5) and F-4MB fluoroplastic are studied. The results from investigating their morphology, molecular composition, and thermal properties are presented.

Microstructure evolution and cooperative reinforcement mechanisms of Al2O3/Al2O3 joints brazed by low-melting borosilicate glass

The Al2O3/SiO2–B2O3–Al2O3–Na2O glass/Al2O3 joints reinforced cooperatively by glass matrix and in-situ Al4B2O9 whiskers were obtained via a low-melting borosilicate glass braze. The composition of glass seam transformed from SiO2–B2O3–Na2O to SiO2–B2O3–Al2O3–Na2O due to continuous diffusion and dissolution of Al2O3. An appropriate amount of [AlO4] units introduced into the glass braze played a vital role in strengthening the glass network structure resulting to considerably improved mechanical strength of the glass seam. Meanwhile, plenty of in-situ Al4B2O9 whiskers growing from the Al2O3/glass braze interface to the center of glass seam in various directions generated. Three-dimensional crisscross structures were fabricated at the Al2O3/glass braze interface domains, where were enhanced by crack-bridging and pull-out effect of the whiskers. Generally, ascribed to the cooperative reinforcement of the glass matrix in the seam and in-situ Al4B2O9 whiskers at Al2O3/glass braze interface domains through reactions of Al2O3 and borosilicate glass braze, strength of the as-brazed joints was promoted prominently. The shear strength of the joints reached a maximum of 61 MPa brazed at 1050 °C for 60 min.